The present invention relates to an
amyloid β
peptide analogues comprising an
amino acid sequence or a
peptidomimetic thereof, wherein the sequence (i) forms a loop, (ii) has at least 66% identity to the
amino acid sequence of native Aβ
peptide or a portion thereof, (iii) comprises at least 6 contiguous
amino acid residues and (iv) has at least 2 non-contiguous amino acid residues which are covalently linked with each other, oligomers comprising a plurality of said
amyloid β
peptide analogues, processes for preparing the
amyloid β peptide analogues or oligomers, compositions comprising the amyloid β peptide analogues or oligomers, and uses of the amyloid β peptide analogues or oligomers such as their use for treating or preventing an
amyloidosis (e.g. by
active immunization), for diagnosing an
amyloidosis, and for providing agents that are capable of binding to the amyloid β peptide analogues or oligomers. The subject invention also describes agents that are capable of binding to the amyloid β peptide analogues or oligomers, e.g. antibodies, compositions comprising the agents, and uses of the agents such as their use for treating or preventing an
amyloidosis (e.g. by passive immunization) and for diagnosing an amyloidosis.